1. Field of the Disclosure
The present application relates to a gate driver and an organic light emitting diode (OLED) display including the gate driver.
2. Discussion of the Related Art
Recently, the development of various flat panel displays is being accelerated. As a type of flat panel display, organic light emitting diode (OLED) displays use self-emitting elements, and thus have a fast response time, excellent emission efficiency, high brightness, and a wide viewing angle.
The OLED display includes an organic light emitting diode (OLED) in each pixel. The OLED includes an organic compound layer formed between an anode electrode and a cathode electrode. The organic compound layer includes a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer. When a driving voltage is applied to the anode electrode and the cathode electrode, holes passing trough the hole transport layer and electrons passing through the electron transport layer move to the light emitting layer to form excitons. As a result, the light emitting layer generates visible light.
The OLED display arranges the pixels each including the OLED in a matrix form and controls brightness of the pixels based on a gray level of video data. The OLED display selectively turns on thin film transistors (TFTs) serving as an active element to thereby select the pixels. Further, the OLED display maintains the light emission of the pixels using a voltage stored in a storage capacitor.
Recently, research is being actively conducted for realizing a three-dimensional (3D) image as well as a two-dimensional (2D) image by using an OLED display as a display device. Among the types of OLED displays that are being currently manufactured for realizing a 3D image, there are a polarization glasses type and a liquid crystal shutter glasses type.
In the liquid crystal shutter glasses type OLED displays, a left eye image and a right eye image are alternately displayed on a display panel in unit of one frame, and left and right eye shutters of liquid crystal shutter glasses open and close in synchronization with a display timing, thereby implementing the 3D image. The liquid crystal shutter glasses open only the left eye shutter during nth frame periods, in which the left eye image is displayed, and open only the right eye shutter during (n+1)th frame periods, in which the right eye image is displayed, thereby making binocular disparity in a time division method.
The OLED display includes a gate driver for driving gate lines formed in the display panel. In other words, the OLED display includes a scan driver for driving scan lines and an emission driver for driving emission lines. The scan driver supplies a scan pulse for determining an addressing time of data to the scan lines, and the emission driver supplies an emission pulse for determining a light emitting time of the pixels to the emission lines. During a period in which data is addressed, the scan pulse of a turn-on level (or an active level) and the emission pulse of a turn-off level (or an inactive level) are generated. During a period in which the pixels emit light, the scan pulse of the turn-off and the emission pulse of the turn-on level are generated. The gate driver is formed in a non-display area of the display panel through the same process as the TFTs of the pixels based on a gate-in-panel (GIP) type.
In the GIP-based gate driver, the emission driver receives the scan pulse from the scan driver and generates the emission pulse with the scan pulse. The scan pulse is generally generated so that a phase of the scan pulse having a predetermined width is shifted by about one horizontal period. Thus, the emission pulse is inevitably generated depending on the scan pulse such that the phase of the emission pulse is shifted by about one horizontal period.
As a result, the related art GIP-based gate driver is merely applied to a sequential light emission for realizing the 2D image as in a portion A of FIG. 1 and is not applied to a simultaneous light emission for realizing the 3D image as in a portion B of FIG. 1. To realize simultaneous light emission, the emission pulses respectively supplied to all of the emission lines are required to be simultaneously generated at the turn-on level in a period in which the left eye image or the right eye image is displayed.